Process of producing commercial hydrochloric acid



Patented A r. za'ieza h4 5 UNITED STATES PATENT OFFEQE.

HUGH A. GELT, AKRON, OHIO, ASSIGNOR TO PITTSBURGH PLATE GLASS COMPANY,

. A CORPORATION OF PENNSYLVANIA.

PROCESS OF PRODUCING COMMERCIAL HYDROCHLOBIC ACID. No Drawing. Application filed March 23, 1923. Serial No. 627,091. v

Ta all whom it may concern: practically acid free. Before such Washing, Be it known that I, HUcr-I A..GALT, a citithis filtered sulphate will carry about 6 per zen of the United States, and a resident of cent of free hydrochloric acid. The calcium Akron, in the county of Summit and State sulphate as thus washed may be either dried 5 of Ohio, have made a new and useful inand marketed in this condition as a com- 60 vention in Improvements in Processes of mercial product, or may be roasted in suit- Producing Commercial Hydrochloric Acid, able furnace, where it loses .75 per cent of of which the following is a specification. its water of crystallization, having the for- The invention relates to a process 'of utimula (2CaSO,,H O), thus producing a .10 lizing a calcium chloride solution such as highly desirable and marketable product, 85

that produced in the practice of the process known as plaster of Paris. set forth in my Patent No. 1,24%),7 39. Such The wash water resulting from the washa solution inay' be evaporated to produce ing of the calcium sulphate containing the commercial calcium chloride, but can be utifree acid and a small amount of calcium sul- 1 lized to better advantage to produce matephate in solution from such sulphate is now vI0 rial more desirable for the industries, such employed in diluting commercial. sulphuric as, plaster of Paris, hydrochloric acid, liquid acid to about 50 Baum, for use in the chlorine and bleaching powder, by followoriginal reaction, so that the hydrochloric ing the procedure as hereinafter set forth. acid and sulphate of calcium, which would p In carrying out the process, the by-prod-. otherwise be lost, is returned to the cycle of 7 net utilized is .the calcium chloride solution '0 eration and utilized. The reactions as referred to above as produced i:by thePwaste a ove recited are as follows:

-,1ime mud recovery process o' my atent No. 1,249,739 which has a specific gravity CaC12+H2S0*+2H2O CasO 2H 0 +2110,

of approximately 1.40, and contains ap- 2 Cas0 2H 2 proximately 40 per cent of calcium chloride. 2 '5 S0 O+3H O This liquor is treated with sulphuric acid a 2 2 (H of such a degree of concentration The hydrochloric acid as produced by the that it will precipitate calcium sulppate process is highly adapted for the produc- 30 with two molecules of water (CaSO Z 0) tion of chlorine by the Weldon process, for 5 together with hydrochloric acid (HCl), of the manufacture of liquid chlorine, bleachthe usual commercial concentration (18 ing powder and other allied products, while Baum). The solutions employed are relathe calcium sulphate may be utilized to adtively strong in order to get high test hydrovantage in producing plaster of Paris. This chloric acid-suitable for the manufacture of utilization of the calcium chloride is desirchlorine, and in order to get a proper and able, "since the amount of calcium chloride complete reaction, it is desirable that the available for manufacture as such is in exmixture should stand from 24 to 36 hours. cess of the demand and it is more profitable It is important that high test hydrochloric to utilize thecalcium chlorid raw material acid be produced by the reaction, as otherto produce the products as above recited, in-

wise the acid would be of little or no value cludin the plaster of Paris, the high test commercially, because of the impracticabilhydroc loric acid, liquid chlorine, bleaching ity of concentrating it to produce a salable powder, and the like. The advantage of the product. p process, for the above reason, and because of 45 The mixture thus produced, consisting of the economy incident to the cycle of operacalcium sulphate precipitate together with tions as recited, will be readily apparent to the hydrochloric acid, is then passed to a those skilled in the art; It is, of course,- ob- 1 suitable mechanical filter where the, acid is vious that the calcium chlorid solution will scparatedfrom the sulphate. This hydrovary in its percentage content of calcium chloric acid, is as above pointedout of the chlorid. One of the important points of concentration ordinarily used in the manunovelty in my invention is the use of a calfacture of chlorine and is used in other arts cium chlorid solution which is strong enough and industries. to permit the direct production of concen- The calcium sulphate is now Washed with trated commercial hydrochloric acid withwater on a suitab e filter, and is rendered out the intermediate step of concentration. 0

drochloric acid which consists in treating a solution of concentrated calcium chloride with sulphuric acid of such degree of concentration as to produce precipitated calcium sulphate and commercial concentrated "hydrochloric acid, allowing the mixture to stand and react, and filtering oil" the acid.

2. A process of utilizing a concentrated solution of calcium chloride which consists in treating such solution with dilute sulphuric acid to produce precipitated calcium sulphate and commercial concentrated hydrochloric acid, filtering oil the acid, washing the calcium sulphate with Water, and utilizing the Wash mixture consisting of water and hydrochloric acidthus obtained to dilute the sulphuric acid for use in the first step of the process as above recited and repeating the cycle.

3. A process of producing commercial hydrochloric acid which consists in treating a solution of calcium chlorid containing approximately 40 per cent of calcium chlorid with sulfuric acid of'suchcdegree of concentration as to produce precipitated calcium sulfate andcommercial concentrated hydrochloric acid and recovering the calcium sulfate and the hydrochloric acid.

In testimony whereof, I have hereunto subscribed my name this 19th day of March,

HUGH A. GALT. 

